A tubular instrument panel reinforcement has conventionally been known that is provided inside the instrument panel of a vehicle along the width direction of the vehicle (see Patent Document 1). The instrument panel reinforcement comprises a large-diameter portion arranged on the driver side to support the steering column and a small-diameter portion arranged on the passenger side to support the air conditioner, etc. The large-diameter portion and the small-diameter portion are coupled together chiefly by fitting them together.